Function timestamp

cpp/src/arrow/type.cc:3186–3188

}

std::shared_ptr<DataType> timestamp(TimeUnit::type unit) {
  return std::make_shared<TimestampType>(unit);
}

std::shared_ptr<DataType> timestamp(TimeUnit::type unit, const std::string& timezone) {
  return std::make_shared<TimestampType>(unit, timezone);